How Do You explicate the Iq Scores?

What is a good Iq score? This is one of the most coarse question one asks, particularly after looking out their score on a test.

There are dissimilar types of tests with each having their own scale. Hence two population having the same score on dissimilar scales might not necessarily have the same intelligence level. However all tests and scales use 100 as the Iq of a someone of midpoint intelligence.

Since the midpoint score is said to be 100, hence anyone above 100 is determined as above midpoint and below 100 as below average. Any score below 70 is taken as that of mentally challenged person. Score above 140 is generally determined as that of a genius.

We already know that Iq = thinking Age/Chronological Age X 100

Hence, the normal or midpoint score is 100, which means that the thinking and chronological ages coincide.

It is true that modern intelligence tests now apply statistical methods to produce a score reflecting one's operation compared to the midpoint operation of his peers. However, the normal or midpoint score will always remain 100.

Let us see why?

When we plot a sample of the population's scores on an Iq against division chart, it is observed that the population distribution on the Iq scale forms a symmetrical bell-shaped curve. This is known as the "Iq Scale Bell-Curve". It reveals that on a scale of 60 to 100, the whole of population with those scores increases and maximum population touch the 100 mark. Then, as the scale increases from 100, the division of population with those scores starts decreasing in proportion to the start of the curve. A very small division of the population reaches over 140.

From this chart, it can be thus complete that a normal score is generally determined to be around the 100 mark.

The scores are thus calculated on a scale of 0 to 200. A someone scoring zero would be surely brain dead, while a score of 200 would mean that the someone is probably the smartest someone alive on the earth.

Since the first Iq test was developed by Alfred Binet and Theophile Simon and their Iq was classified on Simon-Binet scale which was later revised by Lewis Terman into Stanford-Binet scale, this is the most popularly used scale till date and all other modern scales also revolves around it.

According to Standford-Binet scale:

• Over 140 - Genius or practically genius
• 120 - 140 - Very superior intelligence
• 110 - 119 - superior intelligence
• 90 - 109 - midpoint or normal intelligence
• 80 - 89 - Dullness
• 70 - 79 - Borderline deficiency in intelligence
• Under 70 - Feeble-mindedness

Apart from the Standford Binet-Scale, an additional one scale popularly used is the Wechsler scale. According to this scale:

• Over 130 - Very superior
• 120 - 129 - Superior
• 110 - 119 - High average
• 90 - 109 - Average
• 80 - 89 - Low average
• 70 - 79 - Borderline
• Under 70 - very low/intellectually deficient

Besides, these two scales which use a acceptable deviation of 15, an additional one scale in popular use is the Cattell's scale which uses a acceptable deviation of 24. According to Cattell's scale:

• Over 160 - Genius Level
• 140 - 159 - very Intelligent
• 120 - 139 - Above Average
• 100 - 119 - Average
• 90 - 99 - Below Average